Presentation is loading. Please wait.

Presentation is loading. Please wait.

What is an Earthquake  Over 30,000 happen each year worldwide that are strong enough to be felt  Only about 75 major earthquakes take place each year.

Similar presentations

Presentation on theme: "What is an Earthquake  Over 30,000 happen each year worldwide that are strong enough to be felt  Only about 75 major earthquakes take place each year."— Presentation transcript:


2 What is an Earthquake

3  Over 30,000 happen each year worldwide that are strong enough to be felt  Only about 75 major earthquakes take place each year many in remote regions Powerful Earthquake Reported in Costa Rica - YouTube

4  A vibration of the Earth produced by the rapid release of energy  Caused by slippage along a break in Earth’s crust

5  Focus – point within earth where the earthquake starts › Waves are produced here  Epicenter – location on the surface of Earth directly above the focus

6  Faults – fractures in earth’s crust and mantle where movement has occurred

7  Elastic rebound hypothesis – explanation for the release of energy stored in deformed rocks Earthquakes - Shock Waves Explained - YouTube

8  Rocks are in the original position  Stress builds up due to tectonic forces › Builds energy  Energy is released › Earthquake  Land rebounds into new position How Earthquakes Work - YouTube

9  Aftershocks – movements that follow a major earthquake › Sometimes destroy structures weakened by the quake

10  foreshocks - Small earthquakes happening before the major quake › Can be felt days or even years before

11 Measuring Earthquakes

12  Instruments that record earthquake waves

13  2 types › Surface waves › Body waves seismic waves - YouTube

14  Travel along earths outer layer  Up and down as well as side to side motion  Especially damaging to buildings  Slower than body waves

15  Pass through earth’s interior  P waves – push – pull or compression waves › Faster than S waves  S waves – shake particles at right angles › Cannot pass through gases or liquids S and P waves - YouTube

16  Seismographs can be used to see the difference in velocity between p and s waves  Interval between 1 st p wave arrival and 1 st s wave arrival › Longer the interval the further the distance from the earthquake  Uses 3 or more seismographs


18  2 types of measurement › Intensity  Amount of shaking based on damage  qualitative › Magnitude  Calculations of energy released using seismographs  Quantitative

19  Based on amplitude of largest seismic wave  Logarithmic › 10 fold increase in wave amplitude of 1 on the magnitude scale  5.0 is 10X greater than 4.0  Familiar but outdated

20  Based on amount of displacement at a fault zone  More precise  Many different factors › Av. amount of movement › Area of surface break › Strength of broken rock  Most widely used because it measures amount of energy released

21 Destruction from earthquakes

22  Depends on several factors › Intensity and duration › Nature of the material on which the structure is built › Design of the structure

23  Where loosely consolidated sediments are saturated with water, stable soil can turn to a liquid during earthquakes  Buildings may settle and collapse  Underground storage tanks and sewage lines may float to the surface liquefaction

24  Destructive waves › Aka tidal waves  Not actually anything to do with tides  Slab of ocean floor is displaced vertically along a fault  Or when a quake sets off an underwater landslide Japan Tsunami first wave ground footage - YouTube

25  Landslides – do the greatest damage › Soil and / or rock slopes fail  Fire – gas and electrical lines may be cut › when water lines are also cut, fires cannot be stopped – San Francisco 1906

26  &view=detail&id=EE1FD8ED426AAF3B77312E9A9484D8B 0658EAC20&first=1 &view=detail&id=EE1FD8ED426AAF3B77312E9A9484D8B 0658EAC20&first=1  &view=detail&id=0728B2E8AF7D936E47C7BF9A02B44B9 7B405CF78&first=1 &view=detail&id=0728B2E8AF7D936E47C7BF9A02B44B9 7B405CF78&first=1  +fault&view=detail&id=FA2489321AD8DF470812AF17BE 0995E91DC3A1C6 +fault&view=detail&id=FA2489321AD8DF470812AF17BE 0995E91DC3A1C6  +fault&view=detail&id=40D683DDF14E595D6D4E9C9CF 4E6F0AF6CD34876 +fault&view=detail&id=40D683DDF14E595D6D4E9C9CF 4E6F0AF6CD34876  picenter&view=detail&id=FB2A1080B026570F0D431369 A72135CFDE80F499 picenter&view=detail&id=FB2A1080B026570F0D431369 A72135CFDE80F499  picenter&view=detail&id=5946B7F86F88FEDF8AEAAF8D 365662ADEA32DC7B picenter&view=detail&id=5946B7F86F88FEDF8AEAAF8D 365662ADEA32DC7B  rs+of+earth&view=detail&id=36DC8F18B91F95FB51F5D6 AE26A6B8989CFA9262 rs+of+earth&view=detail&id=36DC8F18B91F95FB51F5D6 AE26A6B8989CFA9262  2.jpg/91060621/af1-2.jpg 2.jpg/91060621/af1-2.jpg  nd+hypothesis&view=detail&id=324E2B8DBD877E7D1F2 75E3EA579513E54AD1B37 nd+hypothesis&view=detail&id=324E2B8DBD877E7D1F2 75E3EA579513E54AD1B37  nd+hypothesis&view=detail&id=7062BC2EA8C716E24F9 C497D66852D25DBBCCF7C nd+hypothesis&view=detail&id=7062BC2EA8C716E24F9 C497D66852D25DBBCCF7C  view=detail&id=8853BBAD1093CE083BA03EACCF30069 118E4964F view=detail&id=8853BBAD1093CE083BA03EACCF30069 118E4964F  ew=detail&id=D1940E7C9DDB185FE9A0627D885B1E225 87545B8 ew=detail&id=D1940E7C9DDB185FE9A0627D885B1E225 87545B8  mograhs&view=detail&id=E40AAF20E3AAFDF2518CF57 BF82D246432021C20 mograhs&view=detail&id=E40AAF20E3AAFDF2518CF57 BF82D246432021C20  mograhs&view=detail&id=83C14F9337C971D280DD7DB B312D5330507EE293 mograhs&view=detail&id=83C14F9337C971D280DD7DB B312D5330507EE293  &view=detail&id=CBCC79FBD4D64BC13E8303C4A3EC A227DCA919A3 &view=detail&id=CBCC79FBD4D64BC13E8303C4A3EC A227DCA919A3  rthquakes&view=detail&id=AEC862B742E9419C10F2E53 3EEBE78AABEA7FDC9 rthquakes&view=detail&id=AEC862B742E9419C10F2E53 3EEBE78AABEA7FDC9  rthquakes&view=detail&id=33B413C8FEF8F53B2FAFAB1 313C2C8A33A1801D2 rthquakes&view=detail&id=33B413C8FEF8F53B2FAFAB1 313C2C8A33A1801D2  E3600021-P_and_S_seismic_body_waves,_artwork- SPL.jpg E3600021-P_and_S_seismic_body_waves,_artwork- SPL.jpg  +p+waves&view=detail&id=D48D39E039FEEE7140C6332 5836489C38C9C614F +p+waves&view=detail&id=D48D39E039FEEE7140C6332 5836489C38C9C614F  kes&view=detail&id=03AD9F4CEADBC08D30ECFFBA469 757A1B281DBB1 kes&view=detail&id=03AD9F4CEADBC08D30ECFFBA469 757A1B281DBB1

27  zones&view=detail&id=A3F9FB5A69E1D039843C525F1B AF88159C66E083 zones&view=detail&id=A3F9FB5A69E1D039843C525F1B AF88159C66E083  arthquakes&view=detail&id=B0094EED325431622BDF19 EFA2AFAD11E44F9666 arthquakes&view=detail&id=B0094EED325431622BDF19 EFA2AFAD11E44F9666  &view=detail&id=68579F29E8CD762823EC891EB5C8794 EC51EA709 &view=detail&id=68579F29E8CD762823EC891EB5C8794 EC51EA709  gnitude&view=detail&id=4D878897FBCA6B4E3805C804 7D0365FAFAC739BB gnitude&view=detail&id=4D878897FBCA6B4E3805C804 7D0365FAFAC739BB  damage+to+buidlings&view=detail&id=F5E5C8B45E5F4 5F6F091631C2EC236065EEFC0CD damage+to+buidlings&view=detail&id=F5E5C8B45E5F4 5F6F091631C2EC236065EEFC0CD  arthquake+bolts&view=detail&id=4C0D502CDE305E8C 0BEE8908E67832D33E95ABC7 arthquake+bolts&view=detail&id=4C0D502CDE305E8C 0BEE8908E67832D33E95ABC7  view=detail&id=4EC6832420397B19256452B646F02EB09 D096D33 view=detail&id=4EC6832420397B19256452B646F02EB09 D096D33  view=detail&id=328A257C25776AD3AF663F9412F83BF7E 34EC497 view=detail&id=328A257C25776AD3AF663F9412F83BF7E 34EC497  w=detail&id=C188859273F9A8265A46DCF056BE058E956 8162C w=detail&id=C188859273F9A8265A46DCF056BE058E956 8162C  w=detail&id=9038EBFBAC6EE01E540C37E623206AE422A B9A39&first=119 w=detail&id=9038EBFBAC6EE01E540C37E623206AE422A B9A39&first=119  andslides&view=detail&id=1B54A1285A4A2D03E769A8F 49A2E86E26F1E4F84 andslides&view=detail&id=1B54A1285A4A2D03E769A8F 49A2E86E26F1E4F84  ires&view=detail&id=979D85852B95F1347D623BFE9D272 8FDAF28FD42 ires&view=detail&id=979D85852B95F1347D623BFE9D272 8FDAF28FD42

Download ppt "What is an Earthquake  Over 30,000 happen each year worldwide that are strong enough to be felt  Only about 75 major earthquakes take place each year."

Similar presentations

Ads by Google